The long-term goal of this project is to wed state-of-the-art technology for imaging the vocal tract with a linguistically informed analysis of dynamic vocal tract constriction actions in order to understand the control and production of the compositional units of spoken language. We have pioneered the use of real time MRI for speech imaging to illuminate articulatory dynamics and to understand how these emerge lawfully from the combined effects of vocal tract constriction events distributed over space (subparts of the tract) and over time. This project has developed and refined a novel real time MRI acquisition ability, making possible current reconstruction rates of up to 96 frames per second, quadrupling current imaging speeds. Data show clear real- time movements of the lips, tongue, velum and epiglottis, providing exquisite information about the spatiotemporal properties of speech gestures in both the oral and pharyngeal portions of the vocal tract. The project has also developed novel noise-mitigated image-synchronized strategies to record speech in-situ during imaging, as well as image processing strategies for deriving linguistically meaningful measures from the data, demon- strating the utility of this approach for linguistic studies of speech communication in a variety of languages. Using our direct access to dynamic information on vocal tract shaping, we investigate vocal tract shaping in three-dimensions as the composition of spatiotemporally coordinated vocal tract action units. This project's specific aims go beyond the dynamic shaping of individual vowels and consonants-postures over time-to examine more complex structuring of articulation-namely, the local and global influences governing linguistic control, temporal coherence and multi-unit coordination. The advances in our technical approach enable a series of studies that leverage: (i) unprecedented high-speech imaging with dynamic rtMRI to consider the prosodic modulation of temporally rapid and temporally coherent speech units; (ii) innovative multi-plane 3D imaging capability to inform the computational identification of linguistic control regimes; and (iii) a large- scale rtMRI corpus ad concomitant machine learning advances to move toward a principled account of system-level co-variability in space and time, both within and among individuals. This symbiotic theory-driven and data-driven research strategy will yield significant innovations in understanding spoken communication. It is no exaggeration to say that the advent of real-time MRI for speech has initiated a dramatic scientific change in the nature of speech production research by allowing for models of production driven by rich quantitative articulatory data. The project is having broad impact through the free dissemination of the unique rtMRI data corpora, tools and models-already used worldwide for research and teaching-and societal out- reach through its website and lay media coverage. Understanding articulatory compositional structure and cross-linguistic potentialities also has critical translational significance impacting the assessment and remediation of speech disorders, as our collaborative work on glossectomy and apraxia has begun to demonstrate.